The present invention relates to a device for regulating the flow of a fluid, comprising a valve housing having at least two valve connections, which are fluidically connected to one another via a valve chamber, at least one valve seat, which has a fluid connection to the valve chamber and one of the valve connections, a valve element, which has an actuating section located outside of the valve chamber and a closing body located within the valve chamber for the at least one valve seat and an electromagnet having a solenoid armature, which acts upon the actuating section.
A device of this type is known from EP 2 068 056 B1. The known device comprises a two-component valve housing. The two-component valve housing is formed of a lower housing part, through which a fluid (i.e., a liquid or gaseous medium), flows and an upper housing part, on which an actuating device for regulating the flow of the medium is disposed.
A valve chamber and three valve connections, which are fluidically connected to one another via the valve chamber, are provided in the lower housing part. Two of the three valve connections are fluidically connected to the valve chamber via a valve seat, wherein the axes of the two valve seats extend parallel to one another. The two valve seats are controlled by a single valve element, wherein one valve seat is opened and the other valve seat is closed, in an alternating manner.
The valve element is a stamped sheet metal part or a similarly produced metal part of a frame clamped between the two housing parts and a cruciform carrier, which is fixedly connected via the shorter cross arms thereof to webs provided on the frame. The webs are swivellably supported in the valve housing. A sealing element interacting with one of the two valve seats is mounted on the end of each of the longer cross arms.
The frame is supported in a low-friction manner on one side by a closed seal, through which the webs extend and is fluidically separated from the cruciform carrier on the other side. The frame functions as an actuating section of the valve element and is located outside the valve chamber, while the carrier, which is part of the closing body, is located in the valve chamber and comes into contact with medium. When the frame swivels about the webs or the webs swivel in the seal, the cruciform carrier also simultaneously swivels.
The valve element is actuated via an electromagnet, which acts on the first end of the frame via the axially displaceable solenoid armature thereof. A valve closing spring and a pressure member are disposed between the solenoid armature and the first end of the frame and press the first end of the frame and, therefore, the sealing element disposed there in the direction of the first valve seat.
The second end of the frame and, therefore, the sealing element provided there are pressed via a compression spring and a pressure member in the direction of the associated second valve seat.
The closing force applied by the compression spring is less than the closing force applied by the valve closing spring and therefore, the first valve seat is closed when the electromagnet is de-energized.
When the electromagnet is energized, i.e., activated, the solenoid armature is displaced axially such that the first sealing element is lifted off of the first valve seat via the action of the compression spring.
The known device therefore creates a double-seat valve, which is controlled by a single valve element and has two separate valve inlets and a common valve outlet, wherein the valve inlets can be alternately connected to the valve outlet.
Document EP 1 536 169 B1 describes a further device for regulating a fluid or gaseous medium. The known device comprises a valve housing having a valve inlet and a valve outlet, and a valve opening, which is disposed between the valve inlet and the valve outlet and is surrounded by a valve seat. The valve opening and the valve seat are disposed in a valve chamber.
The valve seat interacts with a valve element to open and close the valve opening, said valve element being mounted on the first end face of an armature of an electromagnet extending into the valve chamber. The armature is guided so as to be axially displaceable in an armature sleeve, which is inserted into the valve chamber and is sealed therein against the chamber wall.
A fixed armature plug is disposed in the armature sleeve above the second end face of the armature, wherein an adjusting pin accessible from the outside is located in the armature plug and interacts with a valve closing spring disposed in a blind hole of the armature. The valve closing spring therefore bears against the armature on one side and against the adjusting pin on the other side. When the electromagnet is de-energized, the valve closing spring presses the armature and, thereby, the valve element onto the valve seat. The adjusting pin can be used to change the axial preload of the valve closing spring and, therefore, the closing force with which the valve element is seated on the valve seat.
The armature is supported in the armature sleeve on both of the end faces thereof by two flat springs such that the armature is contactlessly located in the armature sleeve with minimum radial play and can be axially displaced without touching the inner wall of the armature sleeve. The upper and lower flat springs have the same design but different diameters and have recesses, which extend in a spiral shape or have similarly resilient recesses.
When the adjusting pin is adjusted, the preload of the valve closing spring is changed and the preload of the upper flat spring also is changed. The preload of the lower flat spring can be changed by axially adjusting the armature sleeve.
When current is supplied to the electromagnet, the armature is displaced axially against the spring force of the valve closing spring and the armature lifts the valve element off of the valve seat, thereby opening the valve opening and, depending on the lift of the valve element, a relatively large or small volume of medium flows from the valve inlet via the valve chamber to the valve outlet.
The valve chamber is continually filled with medium. The medium flows constantly around the valve element and the end face of the armature, therefore.
Although the thusly described solenoid armatures have proven successful in everyday use, said solenoid armatures each have specific disadvantages in terms of their use in analytical and medical technology in particular.
The disadvantage of the device known from EP 1 536 169 B1 is that the axially displaceable, metallic armature extends into the valve chamber due to the design thereof, and therefore comes into contact with the medium, which is unacceptable in analytical and medical technology.
The disadvantage of the device known from EP 2 068 056 B1 is that said device does not permit stepless and/or hysteresis-free flow regulation.